Prepare Citrus Marinade by whisking together all ingredients; combine with tuna in large resealable food storage bag.
Seal bag; turn to coat.
Marinate in refrigerator 1 hour, turning occasionally.
Drain tuna; discard marinade.
Spray cold grid of grill with nonstick cooking spray.
Prepare coals for direct grilling.
Place tuna on grid, 4 inches from hot coals.
Grill 8 to 10 minutes or until tuna flakes easily when tested with fork, turning once during grilling.
Slice tuna into 1/4-inch-thick slices; set aside.
Place 2 cups water in large saucepan; bring to a boil over high heat.
Add beans; cook 2 minutes.
Drain; rinse with cold water and drain again.
Place lettuce on large serving platter and arrange tuna, beans, potatoes, tomato, egg whites and onion on lettuce; sprinkle each serving with olives.
Serve with fat-free salad dressing.
Ready in 1 hour and 15 min.